-1
----------
/ 2\
a*\1 + x /
$$- \frac{1}{a \left(x^{2} + 1\right)}$$
2*x
-----------
2
/ 2\
a*\1 + x /
$$\frac{2 x}{a \left(x^{2} + 1\right)^{2}}$$
/ 2 \
| 4*x |
-2*|-1 + ------|
| 2|
\ 1 + x /
----------------
2
/ 2\
a*\1 + x /
$$- \frac{2 \cdot \left(\frac{4 x^{2}}{x^{2} + 1} - 1\right)}{a \left(x^{2} + 1\right)^{2}}$$